The Source of the Carbon Monoxide in the Classical Belousov−Zhabotinsky Reaction

Abstract

CO and CO2 evolution was measured in a cerium and in a ferroin-catalyzed Belousov-Zhabotinsky (BZ) reaction. These gases were stripped from the reaction mixture by a N2 carrier gas, mixed with H2, converted to methane on a Ni catalyst, and then measured by a flame ionization detector (FID). CO could be detected separately by absorbing CO2 on a soda lime column. In separate experiments it was proven that CO is produced in a reaction of BrO2* radicals with bromomalonic acid (BrMA). To this end BrO2(.-) radicals were generated in two different ways: (i) in the reaction HBrO2 + HBrO3 <--> 2 BrO2(.-) + H2O and (ii) by reducing HBrO3 to BrO2(.-) by Fe(2+). It was found that (.-)OH radicals--produced by Fenton's reagent--can also generate CO from BrMA. We propose that CO can be formed when an inorganic radical (like BrO2(.-) or (.-)OH) reacts with the enol form of BrMA producing an acyl radical which decarbonylates in the next step. Malonic acid (MA)-BrMA mixtures were prepared by a new method modifying Zaikin and Zhabotinsky's original recipe to minimize the production of dibromomalonic acid (Br2MA).

Iodine oxidation by hydrogen peroxide in acidic solutions, Bray-Liebhafsky reaction and other related reactions

“…The k exp values were the same with or without pyrocatechol. As a further test of the effect of radical reactions on reaction (O) kinetics we have added FeSO 4 that produces OH radicals by Fenton's reaction and induces radical reactions during the Belousov-Zhabotinsky 35 and Briggs-Rauscher reactions. 36 The situation is different in our system without malonic acid but it is noteworthy that 2 Â 10 À4 mol l À1 of FeSO 4 has no effect on k exp .…”

Belousov–Zhabotinsky reaction in liquid marbles

“…This gas could be CO 2 and/or CO. It has been reported that CO as well as CO 2 can be evolved from the ferroin catalysed BZ reaction [110]. Travelling waves appeared not to be affected as most had been observed by the time gas evolution had occurred.…”

Reactions of Iodomalonic Acid, Diiodomalonic Acid, and Other Organics in the Briggs−Rauscher Oscillating System

“…The pathways have been studied by Ruoff and co-workers, 25,37 by Gyorgi et. al, 38 and by Wittman, Noszticzius, et al 28,[39][40][41] They showed that the nonradical intermediates TTA, MOA, and OA were present in BZ mixtures or in subsystems and that FA was formed from GOA in BZ mixtures. These same species appear during oxidation of BR products and intermediates by H 2 O 2 and Ce 3+ or Mn 2+ .…”